1. Field of Invention
The present invention provides an ink composition for ink jet recording, which, even on various recording media, especially gloss paper of a printing paper base, can yield images having excellent gloss and color reproduction and, at the same time, can realize excellent ejection stability and recovery from clogging, and a method for ink jet recording using the ink composition.
2. Background Art
Ink jet recording is a printing method wherein droplets of an ink are ejected and deposited on recording media, such as paper, to perform printing. An innovative advance of a recent ink jet recording technique has made it possible to realize the production of images having quality comparable to images produced by silver salt photography or images yielded by high-definition printing realized only by offset printing. This trend has led to the development of inks for ink jet recording that can realize images having a high level of gloss comparable to the gloss of images produced by silver salt photography, using the so-called specialty papers which are recording media having a high level of gloss comparable to photographic paper, art paper and the like used in the field of silver salt photography and offset printing. Further, inks for ink jet recording which can realize image quality comparable to the image quality of images produced by silver salt photography even on plain paper, have also been developed.
Inks, which have been generally used for ink jet recording, are water-based inks that comprise water as a main component and a colorant and various additives. Regarding the colorant, the development of pigment-based inks utilizing the properties of the pigment has recently been forwarded because pigments are superior to dyes in weatherfastness properties such as lightfastness, gasfastness, waterfastness, and moisturefastness. For example, Japanese Patent Laid-Open No. 194500/2005 discloses a pigment-based ink having feathering- or bleeding-free properties and excellent gloss on specialty papers that have been realized by using a polysiloxane compound as a surfactant and adding an alkanediol such as 1,2-hexanediol as a solubilizer additive to the ink. Further, Japanese Patent Laid-Open Nos. 72905/2001 and 12583/2003 disclose an ink containing 1,2-hexanediol, which is a water soluble alkanediol, and 1,5-pentanediol, which is a water soluble alkanediol having a hydroxyl group at both ends of its main chain, as additives. The claimed advantage of this ink is feathering- or bleeding-free properties on plain papers.
In recent years, spreading of a technique for image formation from digital data and consideration to natural environment have led to needs, particularly in photographic markets, for ink jet printed matter that can reduce the necessary amount of chemical substances to be used and the amount of waste liquid to be treated, and an ink jet recording system has begun to be applied also in minilab shops. In minilab, color reproduction and stable reproduction of ink jet recorded matter of a printing paper base similar to silver salt photographs are required, and glossy impression comparable to that of silver salt photographs is also required. Further, in recent years, services in which such recorded matter is put into a glassed-in frame immediately after printing and is then handed to a customer on site or is then sent to a customer by mail, are advanced. Putting the ink jet recorded matter into a glassed-in frame immediately after printing, however, sometimes causes dew formation on the glass in the case of some recording media and service environment.
The use of a high-penetration ink containing the above polysiloxane surfactant and 1,2-hexanediol as a solubilizer for the polysiloxane surfactant from the viewpoint of solving the above problem can improve the glossy impression, but sometimes poses a problem of the handleability of the ink jet recorded matter.